A morphological, karyological and chemical study of the Apteranthes (Caralluma) europaea complex

The Apteranthes europaea complex (Apocynaceae–Asclepiadoideae–Ceropegieae–Stapeliinae) distributed from Morocco/southern Spain along the North African coast of the Mediterranean Sea up to Sinai, Negev and southern Jordan is studied with emphasis on stem and flower morphology by SEM, chromosome sizes and flavonoid compounds. Apteranthes europaea was found to be rich in rather uncommon flavone glycosides. Of these, luteolin 4′-neohesperidoside represents the major flavonoid of all samples; luteolin-3′-O-(6′-O-sinapoylglucoside)-4′-O-neohesperidoside and luteolin-3′-O-(6′-O-feruloylglucoside)-4′-O-neohesperidoside are reported here for the first time. Flavonol glycosides also occur, but in much smaller quantities. The different flower morphs, variation in stem and corolla epidermal structures, slight variations in the length of the 2n = 22 chromosomes and in quantitative flavonoid composition are taxonomically best reflected by subdividing the complex into a western var. europaea (Europe and Africa) and an eastern var. judaica (Sinai, Arabia).